FILTRO DE LA MEDIA
A=[25,25,25,25,25;25,35,54,128,25;25,45,35,35,25;25,45,35,35,25;25,25,25,25,25]
B=A;
n=5;
k=1;
for x=1:n-2,
for y=1:n-2,
for i = x:x+2,
for j = y:y+2,
C(k)=B(i,j);
k=k+1;
end;
end;
for l=1:k-1,
for m=1:k-1,
if C(l)>C(m) then
d=C(l);
C(l)=C(m);
C(m)=d;
end;
B(i-1,j-1)=C(5);
end;
end;
k=1;
end;
end;